/* Copyright (C) 2008  Romolo Camplani, Marco Fortunato, Marco Marelli, Guido Rota, Fabio A. Schreiber et al.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 */
package org.dei.perla.parser.expressions;

/**
 * Node d'aggregazione
 * 
 */
public abstract class NodeAggregation extends Node  {

	/**
	 * Tipo di aggregazione
	 */
	private AggregationType aggregationType;
	
	/**
	 * Espressione dell'aggregazione
	 */
	private Node expressionToAggregate;
	
	/**
	 * Eventuale espressione di filtraggio (null se non usata)
	 */
	private Node filterExpression;
	
	public NodeAggregation(AggregationType aggregationTypes, Node expressionToAggregate)
	{
		this.aggregationType = aggregationTypes;
		this.expressionToAggregate = expressionToAggregate;
		this.filterExpression = null;
	}
	
	public NodeAggregation(AggregationType aggregationTypes, Node expressionToAggregate, Node filterExpression)
	{
		this.aggregationType = aggregationTypes;
		this.expressionToAggregate = expressionToAggregate;
		this.filterExpression = filterExpression;
	}
	
	public AggregationType getAggregationType() {
		return aggregationType;
	}
	
	public Node getFilterExpression() {
		return filterExpression;
	}

	public Node getExpressionToAggregate() {
		return expressionToAggregate;
	}
	
	public Class<? extends Object> getAggregationResultType() throws OperationNotSupportedException {
		if (this.aggregationType == AggregationType.COUNT) {
			return ConstantInteger.class;
		}
		else if (this.aggregationType == AggregationType.AVG) {
			return ConstantFloat.class;
		}
		else if (this.aggregationType == AggregationType.MIN) {
			return this.expressionToAggregate.getResultType();
		}
		else if (this.aggregationType == AggregationType.MAX) {
			return this.expressionToAggregate.getResultType();
		}
		else {  // this.aggregationType == AggregationType.SUM
			return this.expressionToAggregate.getResultType();
		}
	}
}
